KR100476631B1 - High storage capacity alloys enabling a hydrogen-based ecosystem - Google Patents

Abstract

A novel magnesium base hydrogen storage alloy suitable and practical for use in the storage and transport of hydrogen for the first time for powering hydrogen powered vehicles and internal combustion engines or fuel cell vehicles. These superior alloys have a significant hydrogen storage capacity of at least 6% by weight and exceptional desorption rate properties such that the alloy powder absorbs 80% of its total capacity within 2 minutes at 300 ° C.

Description

HIGH STORAGE CAPACITY ALLOYS ENABLING A HYDROGEN-BASED ECOSYSTEM

The present invention generally relates to a revolutionary new hydrogen storage compound that enables the first practical use of hydrogen, the most abundant and ultimate fuel source, for the next millennium or more. More specifically, all the necessary attributes can be combined to form a system that enables the safe and efficient storage, transport and delivery of hydrogen to, for example, but not limited to, a powered internal combustion engine or fuel cell engine. The use of hydrogen storage compounds is disclosed.

The present application discloses for the first time a hydrogen storage compound that overcomes chemical, physical, electrical and catalytic barriers that were previously considered insurmountable. The present invention is generally and specifically addressed so far to provide fuel for hydrogen basic ecosystems, such as power internal combustion engines and fuel cell engines, with sufficient hydrogen storage capacity with fast dynamics to enable stable and efficient storage of hydrogen. It is about solving problems that could not be solved. In addition, the present invention solves two basic barriers that prevented the use of the "ultimate fuel": hydrogen storage capacity and hydrogen infrastructure. The infrastructure problem can be solved once there is a storage material that meets the criteria, since hydrogen, when in solid form, can immediately form an infrastructure and be safely transported by boat, lighter, train, truck, etc. to be. The complete infrastructure system from “source to wheel” is the subject matter of US application serial number 09 / 444,810, filed November 22, 1999, which is co-pending. In addition, the use of the alloys of the present invention, due to their ultra-high capacity, solves the problem of social dependence on gasoline by providing motor vehicles over the range of 300 miles.

Here we describe in detail the basic means of designing a hydrogen storage alloy, considering the multi-element Mg-base hydrogen storage materials as a system. These multi-element alloys may be produced in a non-equilibrium manner such that a compositional disorder is created and the desired local chemical order is formed. One aspect of the invention relates to a modified Mg-based hydrogen storage alloy. We first produced Mg-base alloys with hydrogen storage capacity of about 6% by weight or more and having an unusual reaction process. Chemical modifiers and disorders proposed by Stanford R. Ovshinsky (one of the inventors) in a manner that regards the material as a system and thus provides the necessary catalytic local order environment, such as surfaces. By utilizing the principles of local order and simultaneously designing the bulk characteristics of storage and fast charge / discharge cycling, this revolutionary progression is made possible. That is, these principles enable the manufacture of the material by controlling the overall interaction environments on the size, morphology, surface state, catalytic activity, microstructure and storage capacity of the particles and grains.

As the world's population grows and the world's economy expands, the concentration of carbon dioxide in the atmosphere is warming the planet, causing climate change. However, energy systems around the world are steadily escaping from carbon-rich fuels that burn and produce harmful gases. Experts believe that the atmospheric concentration of carbon dioxide will double that of the pre-industrial era by the end of the next century. Says it will be higher despite the trend toward pursuing low-carbon fuels that have been around for over 100 years. In addition, fossil fuels cause pollution and are a source of strategic military warfare between nations.

For about a century and a half, fuels containing large amounts of carbon have been gradually replaced by those containing less carbon. Carbon-rich primary timber was replaced by coal containing less carbon in the late 19th century. And petroleum with low carbon content distillation drove the "King Coal" in the 1960s. Analysts now say that natural gas, a low specific gravity distillation of carbon, will hit its heyday, and the day of hydrogen--providing fuel that contains no carbon at all--will finally come. As a result, experts believe that today's global economy burns less carbon per energy than two-thirds of the carbon produced per unit of energy it burned in 1860.

In the United States, the trend toward low-carbon fuels combined with higher energy efficiency is estimated to have reduced carbon emissions to about half of each economic production unit since 1950. Thus, carbon depletion of energy systems is the only and most important factor from the analysis of these systems over the past 20 years. This gradual change is expected to produce carbon-free energy systems by the end of the 21st century. The present invention shortens the period to several years. In the near term, hydrogen will be used in fuel cells in automobiles, trucks, and industrial equipment, just as it already powers orbital spacecraft. Ultimately, however, hydrogen will also provide a common carbon-free fuel that will meet all fuel shortages.

As you can see from a recent newspaper article, large companies, especially in the United States, have long doubted the global warming claim and have loudly denied the science of climate change. Electric utility companies have even attempted to arouse worries among the public that an international agreement on climate change will hamper economic growth and lead to job loss. Therefore, some of the world's leading companies, such as the two large European oil companies, Royal Dutch / Shell and BP Amoco, once considered it heresy: Global warming is real and needs immediate response. It is very encouraging to say things honestly now. Many US utilities have signed on to find ways to reduce air pollution from their power plants. DuPont, the world's largest chemical company, has voluntarily declared its commitment to reduce greenhouse gas emissions to about 35 levels in the 1990s in the next decade. Automakers, who are significant contributors to the release of greenhouse gas and other pollutants (despite emissions reductions in vehicle standards), have now realized that change is needed, as evidenced by their electric and hybrid vehicles. In this field, the assignee of the present invention has developed an Ovonic nickel metal hydride battery to implement electric and combined vehicles.

Excerpted from a reliable industry source, FIG. 1 is a graph showing the change of society into a carbon-free environment as a function of time from the early 1800s of tree use to about 2010 when the "hydrogen" economy began. In the 1800s, fuel was predominantly wood with a hydrogen-to-carbon ratio of only 0.1. As society changed with the use of coal or oil, the ratio of hydrogen to carbon increased from the initial 1.3 to two. Today, society is moving closer to the use of methane, which has increased its carbon-to-hydrogen ratio to four. However, the ultimate goal for society is to use carbon-free fuels, pure hydrogen, the most common of the elements. Obstacles were the solid state storage capacity and lack of infrastructure. The inventors of the present patent application found that 7% storage materials with excellent adsorption / desorption reaction rates that enable a stable and high capacity means for the first time to store, transport and deliver pure hydrogen may be further improved by further research efforts. To overcome the obstacle.

Hydrogen is the “ultimate fuel.” In fact, for most people, hydrogen is recognized as the “just” fuel for the next millennium and is not depleted. Hydrogen is the most abundant (95% or more) element in the universe. It is the first element formed by the “big explosion in space creation.” Hydrogen can provide a clean, depleted, clean energy source for the planet that can be produced through various processes of breaking water into hydrogen and oxygen. Can be stored and delivered in solid phase form.The present patent application makes it possible to devise a complete generation / storage / transportation / delivery system for a hydrogen-based economy, see, for example, US Pat. No. 4,678,679 (cf. An economical and lightweight three-junction amorphous silicon solar cell, such as the solar cell described in the present disclosure, disclosed by one of the inventors of the present invention The invention developed by Stanford R. Ovshinsky) can be easily placed adjacent to a water body, where the high open circuit voltage of the solar cell decomposes water into its constituent gases and In addition, by placing such a high efficiency solar panel on a nearby farm, in the water or on the ground, electricity is generated to deliver hydrogen into the metal hydride storage layers comprising the metal hydride alloys of the invention presented herein. The ultra-high capacity of these alloys allows this hydrogen to be stored in solid form for transport by transport, tanker, train or truck as a stable and economical form for end use. In any modern society, life and civilization are fundamentally necessary, and hydrogen is the basic source of energy By using a, instead of the dispute for the domination of fossil fuels it will be ended. "Wheels (from well to wheel) from the genetic", a phrase quoted Now would be a "wheels (from source to wheel) from the source."

In the past, considerable attention has been paid to hydrogen as a fuel or fuel substitute. World oil reserves may be depleted, but the supply of hydrogen is virtually unlimited. Hydrogen can be produced from coal, natural gas, and other hydrocarbons or, preferably, by electrolysis of water, via energy from the sun, which consists primarily of hydrogen and is itself considered a huge hydrogen "furnace". Moreover, hydrogen can be produced without the use of fossil fuels, by electrolysis of water using nuclear or solar energy or any other form of economic energy (eg, wind, waves, geothermal, etc.). Moreover, hydrogen is more expensive than oil at present, but it is inexpensive. Hydrogen has the highest energy density per unit weight of any chemical fuel, and is essentially pollution-free because the main by-product of "burning" hydrogen is water. Thus, hydrogen not only provides a means to help developing countries but also solves many of the world's energy related issues, such as climate change, pollution and strategic dependence on oil.

Hydrogen has a wide range of potential applications as fuel, but the major drawback in the use of hydrogen, particularly in the use of automobiles such as the power of a vehicle, has been the lack of a lightweight hydrogen storage medium that meets the criteria.

The storage of hydrogen as compressed gas requires the use of large and heavy containers. In a steel vessel or tank of a typical design, when hydrogen is stored in the tank at a typical pressure of 136 atmospheres, only about 1% of the total weight consists of hydrogen gas. In order to obtain an equivalent amount of energy compared to gasoline, the vessel of hydrogen gas has a weight of about 30 times that of the gasoline vessel. In addition, large expensive compressors are required for storing hydrogen as compressed gas.

Hydrogen can also be stored as a liquid. However, storage as a liquid presents serious safety problems when used as a vehicle fuel due to the extreme flammability of hydrogen. Liquid hydrogen should also be kept at extremely low temperatures below -253 ° C and is highly volatile on leakage. Moreover, liquid hydrogen is expensive to produce, and the energy required for the liquefaction process is a major proportion of the energy produced by hydrogen combustion. Another drawback of storage as a liquid is the significant loss of hydrogen due to evaporation, which is as high as 5% per day.

Hydrogen storage as a solid hydride can provide more percent weight storage than storage as a compressed gas or liquid in a pressure tank. In addition, storage of hydrogen as a solid hydride is safe and does not cause any safety problems caused when stored in a container as a gas or liquid because it is the lowest free energy state when hydrogen is stored in solid hydride form. to be. Preferred hydrogen storage materials must have a high storage capacity with respect to the weight of the material, an appropriate desorption temperature, good reaction rate, good reversibility, resistance to poisoning by contaminants, including those present in hydrogen gas, and relatively low cost Should be If the material does not have any of these properties, it will not be suitable for a wide range of commercial uses.

High hydrogen storage capacity per unit weight of material is an important consideration in applications where hydrides are not in steady state. Low hydrogen storage capacity relative to the weight of the material reduces mileage and thus the range of the vehicle, making the use of such material impractical. Low desorption temperatures (near 300 ° C.) are desirable to reduce the amount of energy needed to release hydrogen. Furthermore, relatively low desorption temperatures for releasing stored hydrogen are needed to effectively utilize the available exhaust heat from automobiles, machinery, or other similar devices. Co-pending US patent application Ser. No. 09 / 444,810 will describe a thermal management system in which temperatures in the 300 ° C. range can be used economically.

Good reversibility is necessary to enable the hydrogen storage material to be capable of repeated absorption-desorption without serious loss of its hydrogen storage capacity. Good reaction rates are necessary to allow hydrogen to be absorbed or desorbed within a relatively short time period. The resistance to poisoning that a material may experience during manufacture and when used is required to prevent degradation of reliability performance.

Known metal host hydrogen storage materials include magnesium, magnesium nickel, vanadium, iron-titanium, lanthanum, pentanickel and alloys thereof. However, none of the known materials has solved the above-mentioned problems that make hydrogen suitable for storage media with a wide range of commercial uses that revolutionize the power industry and make hydrogen a common fuel.

Therefore, many metal hydride systems have been proposed, but magnesium systems have been intensively studied because magnesium can store more than 7 wt.% Hydrogen. While magnesium can store large amounts of hydrogen, its fundamental problem is extremely low reaction rates. For example, magnesium hydride can theoretically store hydrogen at approximately 7.6 weight percent if calculated by the formula: percent storage = H / M + M, where H is the weight of stored hydrogen and M is the hydrogen The weight of the material (all storage ratios mentioned below are calculated by this formula). Unfortunately, known materials, despite their high storage capacity, have not been useful because they require several days for hydrogen discharge. A storage capacity of 7.6% is theoretically appropriate for loading hydrogen storage for use in power vehicles, but this storage capacity can be used to improve commercial use criteria for a wide range of uses by improving the previously useless materials. To this end, the present invention requires the creation of a magnesium-based alloy that behaves under the principles of disorder.

Magnesium is very difficult to activate. For example, US Pat. No. 3,479,165 activates magnesium to remove surface barriers at temperatures between 400 ° C. and 425 ° C. and 1000 psi for several days to obtain significant (90%) conversion to the hydride state. It is said to be necessary. Furthermore, the desorption of such hydrides typically requires relatively hot heating before hydrogen desorption begins. The above-mentioned patent states that the MgH ₂ material must be heated to a temperature of 277 ° C. before desorption starts, and a significantly higher temperature and time are required to obtain a product that meets the criteria.

Even so, the reaction rate of pure magnesium does not meet the criteria. In other words, it cannot be used. Because of this high desorption temperature, conventional magnesium hydride becomes unsuitable.

Magnesium base alloys have also been considered for hydrogen storage. The two major magnesium alloy crystal structures studied so far were A ₂ B and AB ₂ alloys. In the A ₂ B alloy system, the Mg ₂ Ni alloy has been intensively studied because of its proper hydrogen storage capacity and the generated heat (64 kJ / mol) lower than magnesium. However, since the Mg ₂ Ni has a storage capacity of up to 3.6 wt% hydrogen, the researchers have attempted to improve the hydrogenation properties of such alloys through mechanical alloying, mechanical grinding and elemental substitution. However, 3.6% by weight is never high enough, and the reaction rate is also insufficient.

Most recently, researchers have attempted to produce MgNi ₂ alloys for use in hydrogen storage. In the Hydrogenation Properties of Mg-based Laves Phase Alloys by Tsushio et al. , Journal of Alloys and Compound, 269 (1998), 219-223, Tsushio et al. No hydrides of these alloys were reported, and it was determined that the MgNi ₂ alloy was not successful in producing hydrogen storage materials.

Finally, our inventors studied alloys with high magnesium content or basically modified magnesium. For example, in US Pat. Nos. 5,976,276 and 5,916,381, Sapru et al. Provide mechanically alloyed Mg-Ni-Mo and Mg containing about 75 to 95 atomic percent magnesium for thermal storage of hydrogen. -Fe-Ti material was prepared. These alloys are formed by mixing the elemental components in a ball mill or at a suitable ratio and mechanically alloying these materials for several hours to provide a mechanical alloy. These alloys have improved storage capacity, compared to Mg ₂ Ni alloys, while having low plateau pressures.

Another example of a modified high magnesium containing alloy is disclosed in US Pat. No. 4,431,561 to Ovshinsky et al., Which is hereby incorporated by reference. In the '561 patent, thin films of high magnesium containing hydrogen storage alloys were prepared by a sputtering process. This study is noteworthy in that it has significantly improved storage capacity by applying basic principles, but the present invention described here has gathered all necessary properties such as high storage capacity, good reaction rate and good life cycle. .

In US Pat. No. 4,623,597, the disclosure of which is incorporated by reference, one of the inventors of this patent, Obsinski, is a disordered multicomponent hydrogen storage materials for use as cathodes in electrochemical cells. Was presented for the first time. In this patent, Obsinski describes how disordered materials can be produced to greatly increase hydrogen storage and reversible properties. These irregular materials are formed of one or more of amorphous, microcrystalline, intermediate range order or polycrystalline (lacking long range compositional rules), where the polycrystalline material is phase, composition, translational and It may also include one or more of positional transformations and irregularities, and they may be designed from materials. The structure of the active material in these irregular materials consists of a host matrix of one or more elements and a modifier mixed therewith. The modifiers improve the resulting irregularities in the material, resulting in a larger number and range of catalytically active sites and hydrogen storage sites.

The irregular electrode materials of U. S. Patent No. 4,623, 597 are produced from lightweight and inexpensive elements by quite a number of techniques, which basically guarantee the production of unbalanced metastable phases resulting in high energy and power density and low cost. These low cost and high energy density irregular materials allow Ovonic batteries to be most advantageously used as primary batteries as well as secondary batteries, and are currently available worldwide under license from the assignee of the present invention. It is widely used.

Improvements in local structural and chemical rules of the materials described in the '597 patent were of great importance in obtaining the desired properties. The improved properties of the anode of the '597 patent were obtained by mixing the selected modifier elements into a host base, thereby manipulating the local chemical rules and thus the local structural rules to produce the desired irregular material. This irregular material had the desired electronic arrangement resulting in multiple active sites. The nature and number of storage sites were designed independently of catalytically active sites.

Multi-orbital modifiers, for example transition elements, provide a greatly increased number of storage sites with various available bonding arrangements, resulting in an increase in energy density. The modification technique provides, in particular, a non-equilibrium material having a unique bonding arrangement, orbital overlap and thus a range of bonding sites, with varying degrees of irregularity. Due to the different degrees of orbital overlap and irregular structures, during charge / discharge cycles or dormant periods between them, a slight amount of structural rearrangement results in long cycles and shelf life.

The improved battery of the '597 patent included electrode materials with a tailor-made local chemical environment designed to produce high electrochemical charge, discharge efficiency and high charge output. Manipulation of the local chemical environment of the materials has been made possible by the use of a host matrix, which, according to the '597 patent, has catalytically active sites and hydrogen for hydrogen dissociation. It can be chemically modified with other elements to greatly increase the density of the storage regions.

The irregular materials of the '597 patent are designed to have unusual electronic configurations, resulting from the changing three-dimensional interaction of the constituent atoms and their various orbits. This irregularity arises from the compositional, positional and translational kinetic relationships of the atoms. The selected elements were used to further modify the irregularities by interaction with these orbits, to create the desired local chemical environment.

The internal topology created by these arrangements also allows for selective diffusion of atoms and ions. Because of the catalytically controllable number and type of active and storage regions, the invention described in the '597 patent has made these materials ideal for certain applications. All of the above mentioned properties showed significant quantitative differences and also changed the materials qualitatively to obtain unique new materials.

The irregularities described in the '597 patent can achieve atomic properties in the form of compositional or configurational irregularities provided throughout the material or over many areas of the material. Irregularities can also be introduced into the host matrix by creating extremely microscopic phases in the material that simulate compositional or orderly irregularities at the atomic level by relationship to one phase to another. For example, irregular materials may introduce fine regions of different kinds (s) of crystalline phases, introduce regions of amorphous phase (s), or regions of amorphous phase (s) in addition to those of crystalline phase (s). By introducing them. The interface between these phases can provide surfaces rich in local chemical environments that provide a number of desired locations for electrochemical hydrogen storage.

These same principles can be applied within the phase of a single structure. For example, using the Ovshinsky principles of disorder on an atomic or fine scale, compositional irregularities can be achieved by radically altering the material in a planned way to achieve significant, improved and unique results. Can be introduced into this material.

One advantage of the irregular materials of the '597 patent was their resistance to poisoning. Another advantage was the ability to be modified in a continuous range of various proportions of the modifier elements. This property allows the host matrix to be manipulated by a modifier to have the desired properties: high charge / discharge efficiency, high degree of reversibility, high electrical efficiency, long cycle life, high density energy storage, non-toxic and minimal structural modifications. Hydrogen storage materials can be made or designed.

The difference between chemical and thermal hydrides is fundamental. The thermal hydrogenation alloys of the present invention are designed with a separate class of material with their own basic problems to be solved, and the problems shown in Table 1 are in contrast to the problems to be solved in electrochemical systems.

These same attributes have not yet been obtained for thermal hydrogen storage alloys. Therefore, there is a strong and urgent need in the art for high capacity, low cost, lightweight thermal hydrogen storage alloy materials with exceptionally fast kinetics.

Electrochemical Hydrogen Storage Gas phase (thermal) hydrogen storage material mechanism H ₂ O Molecular Cleavage H ₂ dissociation at the material surface Environment Alkali Oxidation Environment (KOH Electrolyte) H ₂ gas-very toxic by oxygen (does not work in the presence of KOH) Rebound speed Hydrogen storage / release at room temperature Store hydrogen anywhere from 20 ℃ to 100 ℃ thermodynamics Specific range of effective M-H bond strengths Acceptable to any extent M-H bond strength Thermal conductivity Small effect Great effect Electrical conductivity Great effect Small effect Chemical reaction ^{_{M + H 2 O + e -}} ⇔ MH + OH - H ₂ (g) ⇔ 2H

1 is a graph showing the ordinate H / C ratio versus abscissa time, showing the movement of society to carbon-free sources of fuel.

FIG. 2 is a graphical and graphical representation of the properties required by a hydrogen storage alloy in order to have the hydrogen storage alloy having the reaction rate characteristics needed to propel the fuel cell and internal combustion engine.

3 is a graph of the pressure composition temperature (PCT) curve of alloy FC-10 at three different temperatures.

4 is a graph of the PCT curve of alloy FC-76 at three different temperatures.

FIG. 5 is a graph of absorption rate characteristics of FC-76 alloy showing hydrogen uptake (% by weight) at three different temperatures. FIG.

FIG. 6 is a graph of the desorption rate characteristic of FC-76 alloy showing hydrogen desorption rate (% by weight) at three different temperatures.

FIG. 7 is a graph of absorption rate characteristics of FC-86 alloy showing hydrogen desorption rate (% by weight) at three different temperatures.

8 is a graph of absorption rate characteristics of FC-76 alloy powder with two different particle sizes.

9 is a view showing an embodiment of the present invention in which the support means to which the hydrogen storage alloy material is bonded is spirally wound to form a coil.

FIG. 10 shows another embodiment of the invention in which the support means to which the hydrogen storage alloy material is bonded is assembled into a plurality of disk stacks.

11 is a schematic diagram of a hydrogen gas supply system using the alloy of the present invention for powering an internal combustion engine vehicle.

12 is a schematic diagram of a hydrogen gas supply system utilizing an alloy of the present invention for powering a fuel cell vehicle.

Summary of the Invention

 The present invention provides a revolutionary hydrogen ecosystem made possible by using new high capacity, low cost, lightweight thermal hydrogen storage alloy materials with fast reaction rates in the form of magnesium based hydrogen storage alloy powders.

These alloys allow for the first time the storage and delivery of solid state hydrogen in order to power a hydrogen-based economy, in particular to power mobile energy consuming applications such as internal combustion engines or fuel cell vehicles. It became possible to use. The alloy comprises more than about 90 weight percent magnesium, and further comprising: a) at least 6 weight percent hydrogen storage capacity; b) an absorption rate such that the alloy powder can absorb 80% of its total capacity within 5 minutes at 300 ° C .; c) particle size range of 30 to 70 microns; And d) suitable microstructures. More preferably, the alloy powder has a hydrogen storage capacity of at least 6.5 wt%, most preferably at least 6.9 wt%. In addition, the alloy powder can more preferably absorb 80% of the total capacity within 2 minutes at 300 ° C., most preferably within 1 minute 30 seconds. Modifier elements added to magnesium to produce alloys mainly include Ni and Mm (mesh metal), and may also include additional elements such as Al, Y and Si. Thus, alloys typically comprise 0.5-2.5 wt% nickel and about 1.0-4.0 wt% Mm (including Ce, La. And Pr in particular). The alloy may comprise any one or more of 3-7 wt% aluminum, 0.1-1.5 wt% Y, and 0.3-1.5 wt% silicon.

As mentioned above, magnesium stores a large amount of hydrogen. However, hydrogen storage kinetics in pure magnesium are undesirable. That is, pure magnesium can store more than 7.6% by weight of hydrogen, whereas Mg-H bonds are very robust (75 kJ / mol), making it difficult to release stored hydrogen and thus pure magnesium is not a commercially viable hydrogen storage material. Thus, pure magnesium alone is insufficient, but compositional (chemically induced) irregular and structural irregularities (quenching) can be used to generate different distributions of elements using the principle of disorder and local order. Can be. This analysis examines the materials as a system, chemical modifiers and Stanford Egg. The principles of irregularities and local rules, proposed by Stanford R. Ovshinsky (one of the inventors of the present application), have been made possible by using them in a manner that provides a local rules environment for storage. Based on these principles, particle size, topology, surface state, catalytic capacity (including catalyst sites and surface regions), microstructure, nucleation and crystal growth rates on the surface and in bulk, and storage capacity between the structural and lattice By controlling this, the material can be improved. FIG. 2 is a graphical, schematic explanatory view of the properties required for hydrogen storage alloys such that the hydrogen storage alloys have the dynamic properties needed to power fuel cells and internal combustion engines, and systematically illustrate these concepts.

In particular, small particles have the property of bridging the gap between crystalline and amorphous solids. That is, small geometrical arrangements give rise to new physical phenomena. The particles of 50 angstroms are "mostly surface", resulting in new topologies and rare bonding arrangements. Also, 21% of all atoms in the 50 ohmsstrong particles are on the surface and the other 40% are in one atom of the surface.

Thus, the compositional irregularities of the multicomponent fine alloys are large in small particles, for example 50 Angstrom particles, and each element in the 10 element alloy will only show 3% variation in concentration by statistics. For these small particles, quantum confinement effects are evident and band structure effects are hindered.

By applying the principles of atomic design and modification of the local environment, the inventors have been able to improve magnesium to store more than 6 wt.% Hydrogen, while exhibiting significantly increased reaction rate properties that enable economic recovery of stored hydrogen. I found it. Increased kinetics allow hydrogen release at low temperatures, increasing the usefulness of metal hydrides in hydrogen-based energy systems. Therefore, this alloy provides a commercially viable, low cost, low weight hydrogen storage material.

Generally, the alloys contain at least about 90% magnesium by weight and include at least one modifier element. The at least one modifier element makes a magnesium-based alloy capable of storing at least 6% by weight hydrogen and absorbing at least 80% of the total storage capacity of hydrogen in 300 minutes at 300 ° C. More preferably, the improved alloy stores at least 6.5 wt% hydrogen and can absorb 80% of the total storage capacity of hydrogen in 300 minutes at 300 ° C. More preferably, the improved alloy stores at least 6.9 wt% hydrogen and can absorb 80% of the total storage capacity of hydrogen in 1.5 minutes at 300 ° C. Modifier elements include primarily Ni and Mm (misch metal), and may also include additional elements such as Al, Y and Si. Thus, alloys typically comprise 0.5-2.5 wt% nickel and about 1.0-4.0 wt% Mm (mainly Ce and La and Pr). The alloy may also comprise one or more of 3-7 wt% Al, 0.1-1.5 wt% Y and 0.3-1.5 wt% silicon. Some examples will help illustrate the invention.

Example 1

An improved Mg alloy with the name FC-10 was prepared having a composition of 91.0 wt.% Mg, 0.9 wt.% Ni, 5.6 wt.% Al, 0.5 wt.% Y and 2.0 wt.% Mm. Individual raw alloy elements were mixed in a glove box. The mixture was placed in a graphite crucible and charged into a furnace. The crucible had a 2.0 mm boron nitride orifice at its bottom, which was blocked by a removable boron nitride rod. The furnace is deaerated by the pump to a very low pressure and purged with argon three times. The argon pressure in the furnace reached 1 psi and maintained at this pressure until the crucible was heated to 600 ° C. When melting was ready, the boron nitride rod was raised and argon was injected into the furnace under pressure. The molten alloy flows from the graphite crucible through a boron nitride orifice onto a copper wheel that is non-water-cooled and rotates horizontally. The copper wheel rotating at about 1000 rpm solidifies the molten alloy into particles, which protrude from the water-cooled copper cap covering the rotating wheel and fall off into a stainless steel pan where it is cooled slowly. Five grams of solidified alloy flakes were mixed with 100 mg of graphite grinding aid. The mixture was mechanically ground for 3 hours. The ground ally was then sifted to recover material having a particle size between 30 and 65 microns. This alloy has a storage capacity of about 6.5 wt.% Hydrogen and absorbs 80% of its maximum capacity within 5 minutes at a temperature of about 300 ° C. Other properties of the alloy properties are described below.

       Example 2

An improved Mg alloy with the name FC-76 was prepared having a composition of 95.6 wt.% Mg, 1.6 wt.% Ni, 0.8 wt.% Si and 2.0 wt.% Mm. This alloy was prepared in the same manner as in Example 1 except that the furnace temperature was 850 ° C. and the orifice size was 2.5 mm. This alloy has a storage capacity of about 6.9 wt.% Hydrogen and absorbs 80% of its maximum capacity within 1.5 minutes at a temperature of about 300 ° C. Other properties of the alloy properties are described below.

Example 3

An improved Mg alloy of the name FC-86 was prepared having a composition of 95 wt.% Mg, 2 wt.% Ni and 3.0 wt.% Mm. The alloy was prepared in the same manner as in Example 1 except that the furnace temperature was 750 ° C. and the wheel speed was 1400 rpm. This alloy has a storage capacity of about 7 wt.% Hydrogen and absorbs 80% of its maximum capacity within 2.3 minutes at a temperature of about 275 ° C. Another description of the alloy properties is described below.

The alloys of the present invention are unique in the combination of high storage capacity and good absorption / desorption rate properties. The inventors have found that the combination of the alloy composition and the particle size of the hydrogen storage alloy has an important effect on the reaction rate characteristics. In other words, the inventors have found that the reaction rate properties of the material (regardless of the specific composition) increase with decreasing particle size. Specifically, the inventors have found that materials having particle sizes between 30 and 70 microns are most useful. This particle size is manufacturable but gives very good reaction rate properties. Increasing the particle size facilitates manufacture, but greatly reduces the kinetics of the material, while reducing the particle size is nearly impossible due to the high ductility of these Mg base alloys. In practice, the use of gas atomization may be required in industry to produce large amounts of particulate alloys. This is especially because alloys are very soft and cannot be effectively crushed.

FIG. 3 is a graph of pressure-composition-temperature (PCT) curves of alloy FC-10 at 279 ° C. (denoted by symbol o), 306 ° C. (denoted by symbol ▲) and 335 ° C. (denoted by Δ symbol). The graph shows that the alloy has a plateau pressure of 1050 Torr at 279 ° C., 2200 Torr at 306 ° C., and 4300 Torr at 335 ° C. The PCT curve shows that the FC-10 alloy has a maximum capacity of about 6.5 wt% hydrogen and a hydrogen bond energy of about 70 kJ / mole.

4 is a graph of PCT curves of alloy FC-76 at 278 ° C. (marked with symbol), 293 ° C. (marked with ◆ symbol), and 320 ° C. (marked with a symbol ▲). The graph shows that the alloy has a stable level pressure of 750 Torr at 278 ° C., 1100 Torr at 293 ° C., and 2400 Torr at 320 ° C. The PCT curve shows that the FC-76 alloy has a maximum capacity of approximately 6.9 wt% hydrogen and a hydrogen bond energy of approximately 75 kJ / mole.

5 is a graph of absorption rate characteristics of FC-76 alloy. Specifically, the weight percent hydrogen uptake versus time is indicated for three temperatures: 275 ° C. (° symbol), 300 ° C. (° symbol) and 325 ° C. (Δ symbol). As can be seen, at 275 ° C the alloy absorbs 80% of its total capacity in 1.3 minutes, at 300 ° C the alloy absorbs 80% of its total capacity in 1.4 minutes, and at 325 ° C the alloy absorbs in 2.0 minutes Absorbs 80% of its total capacity.

6 is a plot of the desorption rate characteristic of FC-76 alloy. Specifically, the weight percent hydrogen desorption rate versus time is indicated for three temperatures: 275 ° C. (□ symbol), 300 ° C. (° symbol) and 325 ° C. (Δ symbol). As can be seen, at 275 ° C, the alloy desorbs 80% of its total capacity in 8.0 minutes, at 300 ° C the alloy desorbs 80% of its total capacity in 3.4 minutes, and at 325 ° C the alloy desorbs in 2.5 minutes. 80% of its total capacity is removed.

7 is a graph of the absorption rate characteristics of FC-86 alloy. Specifically, the weight percent hydrogen uptake versus time is expressed for three temperatures: 230 ° C. (° C.), 240 ° C. (° C.), and 275 ° C. (* symbol). As can be seen, at 230 ° C., the alloy absorbs 80% of its total capacity in 5.2 minutes, at 300 ° C., the alloy absorbs 80% of its total capacity in 2.4 minutes, and at 325 ° C. the alloy takes 2.3 minutes. Absorbs 80% of its total capacity.

8 is a plot of the absorption rate characteristics of FC-76 alloy powders with two different particle sizes. Specifically, hydrogen uptake (% by weight) versus time is shown for materials having a particle size range of 75 to 250 microns (o symbol) and 32 to 63 microns (o symbol). As can be seen, smaller particle size greatly improves the absorption rate characteristic.

In the above embodiments the method of producing the powder was rapid solidification and subsequent grinding, but gas atomization could also be used. When grinding materials, the preferred method of grinding is to use an attritor. In particular, when grinding these alloys, the addition of a grinding agent such as carbon is particularly useful.

The present invention includes metal hydrides as hydrogen storage means for storing hydrogen in containers or tanks. In one embodiment of the present invention, the storage means comprises the above-described hydrogen storage alloy material physically bonded to the support means. In general, the support means may take the form of any structure capable of holding a storage alloy material. Examples of supporting means include, but are not limited to, mesh, grid, matte, foil, foam and plate. Each may be present as a metal or a nonmetal.

The support means can be made of various materials with suitable thermodynamic characteristics that can provide the required heat transfer mechanism. These include both metal and nonmetallic materials. Preferred metals include those selected from the group consisting of Ni, Al, Cu, Fe and mixtures or alloys thereof. Examples of support means that can be produced from the metal include a wire mesh, expanded metal, foamed metal.

The hydrogen storage alloy material may be physically attached to the support means by a compaction and / or sintering process. The alloy material is first made into a fine powder. Thereafter, the powder is compressed and solidified in the number of supporting units. The powder is attached to the supporting means by the compression solidification process to become an integral part of the supporting means. After the compression solidification step, the support means to which the alloy powder is attached is preheated and then sintered. The preheating process releases excess moisture and inhibits oxidation of the alloy powder. Sintering is carried out at a high temperature, substantially inert atmosphere containing hydrogen. The temperature is high enough to cause particle-to-particle bonding of the alloying material and bonding with the support means of the alloying material.

The support means / alloy material may be packaged in many different arrangements within the container / tank. 9 shows an arrangement in which the support means / alloy material are spirally wound to form a coil. 10 shows an arrangement of variants in which the support means / alloy material is assembled as a plurality of laminated disks in a container. Other arrangements are also possible (eg laminated metal plates).

By compression-solidifying and sintering the alloying material on the support means, the packing density and thermodynamic and reaction rate characteristics of the hydrogen storage system are improved. Close contact between the support means and the alloy material improves the efficiency of heat transfer to and from the hydrogen storage alloy material when hydrogen is absorbed and desorbed. In addition, an even temperature and heat distribution is achieved over the entire bed of alloy material by evenly distributing the support means over the interior of the container. The result is a more even rate of hydrogen absorption and desorption throughout, resulting in a more efficient energy storage system.

One problem when using alloy powders alone (without supporting means) in hydrogen storage layers is that of self-compaction due to the reduction of particle size. That is, during repeated cycles of hydrogenation and dehydrogenation, alloying materials expand and contract as they absorb and desorb hydrogen. Some alloying materials have been found to expand and contract by 25% by volume as a result of the introduction of hydrogen into the material lattice and the release of hydrogen from the material lattice. As a result of the dimensional change of the alloying materials, the alloying materials are cracked, broken and crushed into finer particles. After the repetitive cycle, the fine particles are self-compressible, resulting in insufficient hydrogen transfer as well as high stress oriented relative to the walls of the storage vessel.

However, the processes used to bond the alloying material onto the support means keep the alloy particles firmly bonded to each other as well as to the support means during the absorption and desorption cycles. In addition, the rigid packaging of the support means in the container serves as a mechanical support to hold the alloy particles in place during expansion, contraction and destruction of the material.

The present alloy and storage material systems are useful for supplying hydrogen to many applications. One such application is in the automotive sector. Specifically, the systems can be used as a hydrogen source for an internal combustion engine engine (ICE) vehicle or fuel cell (FC) vehicle.

FIG. 11 shows a schematic view of a hydrogen gas supply system for an ICE vehicle for supplying hydrogen gas to the hydrogen internal combustion engine 1. This system supplies the internal combustion engine waste heat transfer supply which induces the internal combustion engine waste heat discharged (in the form of exhaust gas or internal combustion engine coolant) from the hydrogen gas storage section 2 and the internal combustion engine 1 to the hydrogen gas storage section 2. Has a passage (3). The system also includes a return passage 4 for returning all internal combustion engine coolant used to heat the hydrogen storage material back to the internal combustion engine 1 and an exhaust gas pipe 7 for releasing the exhaust gas used. Include. The system further comprises a hydrogen gas supply passage 5 for inducing hydrogen gas from the hydrogen gas storage 2 to the internal combustion engine 1. The waste heat transfer supply passage 3 of the internal combustion engine has a temperature controller 6 for controlling the temperature of waste heat to be introduced into the hydrogen gas storage unit 2. In such a system, waste heat generated in the ICE can be efficiently used to heat the hydrogen reservoir and release hydrogen from the hydrogen reservoir for use in the ICE.

12 is a schematic diagram of a hydrogen gas supply system for an FC vehicle, which is used to supply hydrogen gas to the fuel cell 8. The system has a hydrogen gas storage unit 12 and a fuel cell waste heat / hydrogen transfer supply passage 9 which directs the fuel cell waste heat and unused hydrogen released from the fuel cell 8 to the hydrogen gas combustor 10. Waste heat from the fuel cell may take the form of a heated gas or a heated aqueous electrolyte. The hydrogen burner 10 utilizes waste heat from the fuel cell 8 and also burns hydrogen to heat the heat transfer medium (preferably in the form of a water-soluble electrolyte from the fuel cell). Hydrogen is supplied to the combustor 10 as unused hydrogen from the fuel cell 8 and with fresh hydrogen supplied from the hydrogen storage 12 through the hydrogen supply line 14. The heated heat transfer medium is supplied to the hydrogen storage unit 12 through the supply line 13. The system also includes a return passage 16 for returning any fuel cell water soluble electrolyte used to heat the hydrogen reservoir to the fuel cell 8 and an exhaust gas pipe 15 for releasing the combustor gas used. . The system further includes a hydrogen gas supply passage 11 for guiding hydrogen gas from the hydrogen gas storage 12 to the fuel cell 8.

While the present invention has been described in connection with the preferred embodiments and their order, it will be appreciated that it is not intended to limit the invention to the embodiments and order. On the contrary, the invention covers all modifications, improvements and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims.

Claims (19)

A hydrogen power vehicle apparatus, wherein the apparatus One or more internal combustion engines fueled by hydrogen or fuel cells; And And hydrogen storage means operatively interconnected to the internal combustion engine, wherein the hydrogen storage means comprises a hydrogen storage alloy powder. a) at least 6 weight percent hydrogen storage capacity; And b) wherein said alloy powder comprises a hydrogen storage alloy powder characterized by an absorption rate characteristic such that 80% of its total capacity is absorbed at 300 ° C. within 5 minutes. 2. The alloy of claim 1, wherein the alloy comprises 0.5-2.5 wt% nickel, 1.0-4.0 wt% misch metal, and 93.5-98.5 wt% magnesium, wherein the misch metal comprises Ce, La, and Pr as main elements. Hydrogen powered vehicle device. delete delete delete The method of claim 1, wherein the alloy is 0.5-2.5 wt% nickel, 1.0-4.0 wt% misch metal, 3-7 wt Al, 0.1-1.5 wt% Y, 0.3-1.5 wt% silicon, and 83.5-95.1 weight Hydrogen powered vehicle device containing% magnesium. The hydrogen power vehicle apparatus according to claim 1, wherein the alloy comprises 91.0 wt% Mg, 0.9 wt% Ni, 5.6 wt% Al, 0.5 wt% Y, and 2.0 wt% misch metal. The hydrogen power vehicle apparatus according to claim 1, wherein the alloy comprises 95.6 wt% Mg, 1.6 wt% Ni, 0.8 wt% Si, and 2.0 wt% misch metal. The hydrogen power vehicle apparatus according to claim 1, wherein the alloy comprises 95 wt% Mg, 2 wt% Ni, and 3.0 wt% misch metal. As a magnesium based hydrogen storage alloy powder, the powder is:  a) at least 6 weight percent hydrogen storage capacity; And b) The magnesium basic hydrogen storage alloy powder comprising magnesium powder characterized by an absorption rate characteristic of absorbing 80% of its total capacity at 300 ° C. within 5 minutes. The alloy of claim 10, wherein the alloy comprises 0.5 to 2.5 wt% nickel, 1.0 to 4.0 wt% misch metal, and 93.5 to 98.5 wt% magnesium, and the misch metal comprises Ce, La, and Pr as main elements. Magnesium basic hydrogen storage alloy powder. delete delete The alloy of claim 10 wherein the alloy comprises 0.5-2.5 wt% nickel, 1.0-4.0 wt% misch metal, 3-7 wt Al, 0.1-1.5 wt% Y, 0.3-1.5 wt% silicon, and 83.5-99.5 weight. Magnesium Base Hydrogen Storage Alloy Powder Containing% Magnesium. The magnesium based hydrogen storage alloy powder of claim 10, wherein the alloy comprises 91.0 wt% Mg, 0.9 wt% Ni, 5.6 wt% Al, 0.5 wt% Y, and 2.0 wt% misch metal. The magnesium based hydrogen storage alloy powder of claim 10, wherein the alloy comprises 95.6 wt% Mg, 1.6 wt% Ni, 0.8 wt% Si, and 2.0 wt% misch metal. The magnesium based hydrogen storage alloy of claim 10, wherein the alloy comprises 95 wt.% Mg, 2 wt.% Ni, and 3.0 wt.% Misch metal. delete delete